executor: enable periodic leak checking

This commit enables the periodic execution of a leak checker within the executor. The leak checker will now run every
5000 program executions, but only after the corpus has been triaged and all executor processes are in an idle state.
Fixes #4728.

Author: pimyn-girgis

executor/executor_runner.h

@@ -197,7 +197,6 @@ class Proc
 		return;
 	}
 
-private:
 	enum State : uint8 {
 		// The process has just started.
 		Started,
@@ -209,6 +208,43 @@ class Proc
 		Executing,
 	};
 
+	State GetState() const
+	{
+		return state_;
+	}
+
+	void RunLeakChecker()
+	{
+		debug("proc %d: running leak checker\n", id_);
+		int stdout_pipe[2];
+		if (pipe(stdout_pipe))
+			fail("leak checker pipe failed");
+
+		const char* argv[] = {bin_, "leak", nullptr};
+		std::vector<std::pair<int, int>> fds = {
+		    {-1, STDIN_FILENO}, // We don't need an stdin pipe. No communication is done in the parent -> child direction.
+		    {stdout_pipe[1], STDOUT_FILENO},
+		    {stdout_pipe[1], STDERR_FILENO},
+		};
+		Subprocess leak_process(argv, fds);
+		close(stdout_pipe[1]);
+
+		std::vector<uint8_t> output;
+		for (;;) {
+			const size_t kChunk = 1024;
+			output.resize(output.size() + kChunk);
+			ssize_t n = read(stdout_pipe[0], output.data() + output.size() - kChunk, kChunk);
+			output.resize(output.size() - kChunk + std::max<ssize_t>(n, 0));
+			if (n <= 0)
+				break;
+		}
+		output.push_back(0);
+		fprintf(stderr, "proc %d: leak checker output:\n%s\n", id_, (const char*)output.data());
+
+		close(stdout_pipe[0]);
+	}
+
+private:
 	Connection& conn_;
 	const char* const bin_;
 	ProcIDPool& proc_id_pool_;
@@ -575,6 +611,7 @@ class Runner
 	std::vector<std::string> leak_frames_;
 	int restarting_ = 0;
 	bool corpus_triaged_ = false;
+	uint64 proc_counter_ = 0;
 	ProcOpts proc_opts_{};
 
 	friend std::ostream& operator<<(std::ostream& ss, const Runner& runner)
@@ -623,9 +660,19 @@ class Runner
 
 		for (auto& proc : procs_) {
 			proc->Ready(select, now, requests_.empty());
-			if (!requests_.empty()) {
-				if (proc->Execute(requests_.front()))
+			constexpr uint64 kRunLeakCheckEvery = 5000;
+			if (corpus_triaged_ && proc_counter_ && proc_counter_ % kRunLeakCheckEvery == 0) {
+				if (std::all_of(procs_.begin(), procs_.end(), [](const auto& proc) {
+					    return proc->GetState() == Proc::State::Idle;
+				    })) {
+					proc->RunLeakChecker();
+					++proc_counter_;
+				}
+			} else if (!requests_.empty()) {
+				if (proc->Execute(requests_.front())) {
 					requests_.pop_front();
+					++proc_counter_;
+				}
 			}
 		}